Olympiad Test: Plant Life - 1 - Class 5 MCQ

Trees start preparing for winter when the days become shorter and there are fewer hours of sunlight. This change in sunlight triggers the trees to slow down their growth and get ready for the cold months ahead.

• Option A ("The days become colder") is not the main signal. While it does get colder, it's the reduced sunlight that tells trees to prepare for winter.
• Option B ("The weather becomes dry") may happen in some places, but it is not the main factor.
• Option C ("There are more rainy days") is also not the main reason. Trees mainly react to the amount of sunlight and the change in temperature.

So, the correct answer is Option D: There are fewer hours of sunlight.

In the fall, trees stop producing chlorophyll, which is the green pigment that helps plants make food from sunlight (photosynthesis). As the chlorophyll breaks down and disappears, other pigments in the leaves, like carotenoids (which are yellow or orange) and anthocyanins (which are red or purple), become visible. These pigments were always in the leaves, but the green chlorophyll usually hides them.

• Option A ("The tree has less water") is not the main reason for color change. While water is important, the color change happens because of the reduction in chlorophyll production.
• Option C ("The tree has no leaves") is not correct. The tree still has leaves during fall, but the leaves change color due to the decrease in chlorophyll.
• Option D ("The tree is growing quickly before the winter sets in") is also incorrect. Fall is a time when trees slow down their growth, not speed up.

So, the correct answer is Option B: The tree has less chlorophyll.

When a mango sapling grows too close to the parent tree, it faces several challenges:

• A: May not be able to spread its branches: The sapling will have limited space to grow its branches properly if it is too close to the parent tree, which could cause overcrowding.
• B: May not get enough water: The parent tree, being older and larger, might take up most of the water from the soil, leaving less water for the sapling.
• C: May not get sufficient sunlight: If the sapling is growing under the shade of the parent tree, it may not receive enough sunlight for healthy growth.

Therefore, all of the above are potential issues the sapling could face, making Option D the correct answer.

The roots of plants absorb both nutrients and water from the soil:

• Nutrients: These include essential minerals like nitrogen, phosphorus, potassium, and others that help in the plant’s growth and development.
• Water: The roots also absorb water, which is vital for the plant's hydration, photosynthesis, and overall function.

Thus, the correct answer is C: Both A and B.

In layering, the stem of a plant is used to produce a new plant without detaching it from the parent plant. In this method, a part of the stem is buried in the soil while still attached to the parent plant. Over time, roots form at the buried part, and a new plant grows, which can later be separated from the parent plant.

• Cutting involves detaching a part of the stem to form a new plant.
• Budding involves taking a bud from one plant and attaching it to another plant.

Therefore, the correct method in this case is Layering.

Tribal people often get their food from:

• From trees: They may gather fruits, nuts, and other edible plant parts from trees, such as mangoes, coconuts, and berries.
• By hunting animals: They may also hunt animals like deer, birds, or small game for food.

Unlike people who rely on grocery stores, tribal communities typically rely on nature and their environment for sustenance, which includes both plants and animals. Therefore, the correct answer is D: A and B both.

Bryophyllum is a type of plant that can reproduce through its leaves. The leaves of Bryophyllum have specialized structures that can develop into new plants when they come into contact with soil. This is a form of vegetative propagation, where new plants grow from parts of the parent plant without the need for seeds.

Clayey soil is rich in nutrients and has good water retention capacity, making it ideal for certain crops. Rice and jute are both plants that thrive in clayey soils, as they need more water and moisture to grow. Clayey soil's ability to hold water is beneficial for rice, especially in paddy fields. Similarly, jute also grows well in waterlogged conditions, which is facilitated by clayey soil.

The coconut seed has a thick, fibrous outer covering known as a husk. This husk is made of fibers and helps protect the seed inside from environmental factors, including water. The other seeds, like neem, papaya, and lemon, have relatively thinner and softer outer coverings compared to the fibrous coconut seed.

The cotyledon is the part of the seed that stores food. It acts as the initial food source for the developing seedling before it can begin to photosynthesize on its own. The other parts of the seed, such as the plumule (which develops into the shoot), the root, and the shoot, all play roles in growth and development, but it is the cotyledon that stores nutrients necessary for early growth.